During operations of an aircraft, an onboard diagnostics system collects diagnostics data reflecting the aircraft's performance, operational variables, and operational incidents. The collected diagnostics data may be evaluated by the diagnostics system in order to detect potential faults with the aircraft's systems and components, for example. In some cases, the diagnostics system accesses loadable diagnostics information (“LDI”) in conjunction with evaluating the collected diagnostics data. The LDI may be represented in a binary file, for example, which includes an entity-relationship model relating to various system components. For example, the entity-relationship model may include entities associated with various aircraft components, information defining the relationships between the entities, and attributes of the entities and relationships. To evaluate the aircraft's operation, the diagnostics system applies the collected diagnostics data to the entity-relationship model defined in the LDI.
Typically, a ground-based binary converter tool generates the LDI file, and the LDI file is thereafter loaded into diagnostics system accessible memory prior to aircraft operations. The binary converter tool is constrained to arrange the various entities within the LDI file according to a predetermined binary file structure, and the onboard diagnostics system has a priori knowledge of the predetermined structure. More particularly, the onboard diagnostics system may include an LDI accessor module, and the structure of the LDI file is embedded (e.g., hardcoded) in the LDI accessor module code. This enables the LDI accessor module to calculate the position of each entity within the LDI file, in order to facilitate access by the LDI accessor module to each entity during aircraft operations.
Using traditional techniques, whenever a change is implemented in the structure of an entity-relationship model defined in an LDI file, the embedded LDI file structure information in the LDI accessor module also must be updated. An LDI accessor module typically is a qualified tool in an aircraft, however. Accordingly, updates to the LDI accessor module's embedded software requires a requalification process to be performed. Requalification of aircraft components and systems are time consuming and expensive processes. Accordingly, relatively long delays are inherent in implementing LDI file structure changes (e.g., entity-relationship model changes) using traditional techniques. In addition, even after requalification is completed, the embedded software must be updated in the LDI accessor module of each aircraft in which the newly structured LDI files are to be used. Accordingly, significant time and expense is associated with implementing LDI file structure changes, particularly when extensive aircraft fleets are to be updated. Because LDI file structure changes may be implemented at least several times during the operational life of an aircraft, what are needed are more efficient methods and apparatus to enable LDI file structure changes to be rapidly and inexpensively implemented in conjunction with aircraft diagnostics systems.